Jarod Reyes wanted to reduce his anxiety. His doctor suggested meditation, so he subscribed to a podcast to guide him toward a Zen state.

“Close your eyes,” the podcaster’s voice would intone languidly over instrumental music. “Take a slow, deep breath.” But something about it made him anxious. The episodes were too long; it was hard to focus.

He knew what he had to do. Now the 35-year-old web developer sets the podcast to...